It is known that the presence of excess moisture can affect the condition of numerous products due to the formation of fungi, mould, bad smells or condensation.
At the same time, an environment that is too dry is harmful to other materials. In these conditions, for example, the state of wooden musical instruments can be affected and the flavour and fragrance of foods and spices is altered.
To reduce the moisture in a closed system, desiccating materials are commonly used, generally supplied in breathable bags. The most commonly used include silica gel, activated clay and hygroscopic salts.
However, the limits that make these materials unsuitable for use as moisture regulators are numerous. Firstly, they capture the moisture (until they are completely saturated) even when not necessary, with the risk of making the environment too dry.
A second limit is their poor or null regeneration capacity (i.e. moisture release) once maximum absorption has been reached. In these conditions they become unusable, and to re-activate them they have to be heated to over 100° C., with consequent high energy consumption and poor practicality in terms of use.
A third limit of some of these materials is their deliquescence, a phenomenon that consists in the formation of an aqueous solution following the absorption of moisture by a solid hygroscopic salt. In addition, said solution can contain ions which are potentially corrosive for the material to be protected.
To remedy this problem, various formulations are known in which particles of hygroscopic salt are mixed with thickening materials. However, organic thickeners such as modified starches or sugars have the unfortunate drawback of being an excellent nutrient for the development and proliferation of bacterial growth, especially if used in large quantities.
An important aspect is that the majority of the desiccating products cited above cannot be used in direct contact with food. A solution to this problem may be the use of suitable protective membranes which contain the desiccating material. In this case, however, the moisture absorption speed is inevitably reduced, and at the same time the end cost of the product increases.
In addition to the above, to raise the moisture level in a dry system, humidifiers are usually used which constantly release moisture until they become completely depleted. As described for the desiccants, also in this case the process is not controllable, with the risk of passing from an excessively dry environment to an excessively humid environment.